Protection architecture for virtual channel connections (VCCS) in a telecommunications network

ABSTRACT

A method for protecting virtual channel connection (VCC) traffic in a telecommunications system includes receiving a virtual path connection (VPC) at a destination node. The virtual path connection (VPC) is received on each of a working transmission link and a protection transmission link. The virtual path connection (VPC) includes a plurality of virtual channel connections (VCCs) A protection switching status is received for the working and protection transmission links. The virtual channel connections (VCCs) are selected from the working and protection transmission links for processing by selecting the virtual path connection (VPC) from one of the working and protection links based on the protection switching status for at least one of the working and protection transmission links.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to the field of telecommunicationssystems, and more particularly to a protection architecture for virtualchannel connections (VCCs) in a telecommunications network.

BACKGROUND OF THE INVENTION

Telecommunications networks have traditionally been circuit-switchnetworks that have transmission paths dedicated to specific users forthe duration of a call and that employ continuous, fixed-bandwidthtransmission. Due to growth in data traffic created by the Internet andits related technologies, however, core telecommunications networks arebeing moved to a packet-switching transmission model. Packet-switchnetworks provide a large range of digital services, from data to videoto basic voice telephony. Packet-switch networks can allow dynamicbandwidth and may be connectionless with no dedicated path orconnection-oriented with virtual circuits and dedicated bandwidth alonga predetermined path.

Asynchronous transfer mode (ATM) is a connection-orientedpacket-switching technology in which information is organized intosmall, fixed length cells. ATM carries data asynchronously,automatically assigning data cells to available time slots on demand toprovide maximum throughput. Compared with other network technologies,ATM provides large increases in maximum supported bandwidth, designed-inasynchronous traffic support, support for multiple types of traffic suchas data, video, and voice transmissions on shared communication lines,and virtual networking capabilities, which increase bandwidthutilization and ease network administration.

ATM cells are routed through a telecommunications network at high speedsusing a switching label included in the cell. The switching label hastwo sections that define a virtual path (VP) and a virtual channel (VC)in the network through which the cell is routed. The use of virtualpaths (VPs) and virtual channels (VCs) allows physical bandwidth in thenetwork to be subdivided into virtual channel connections (VCCs) andseparately commercialized.

Within a telecommunications network, virtual channel connections (VCCs)are typically routed along redundant paths to support protectionswitching at a destination node. As bandwidth in transmission lines issubdivided into an increasing number of virtual channel connections(VCCs), however, protection switching for each of the connectionsbecomes difficult to implement. Previous attempts to manage protectionswitching have included bundling together virtual channel connections(VCCs) to form a virtual channel group (VCG) In the event of protectionswitching, all virtual channel connections (VCCS) contained within thegroup are simultaneously switched. Although this improves efficiency,switching nevertheless remains at the virtual channel connection (VCC)level and is resource intensive.

SUMMARY OF THE INVENTION

The present invention provides a protection architecture for virtualchannel connections (VCCs) in a telecommunications network thatsubstantially eliminate or reduce disadvantages and problems associatedwith previous systems and methods. In particular, virtual channelconnections (VCCs) for a protection domain are bundled together into avirtual path connection (VPC) and protection switched at that level inthe event of a transmission line failure.

In accordance with one embodiment of the present invention, a method forprotecting virtual channel connection (VCC) traffic in atelecommunications system includes receiving a virtual path connection(VPC) at a destination node. The virtual path connection (VPC) isreceived on each of a working transmission link and a protectiontransmission link. The virtual path connection (VPC) includes aplurality of virtual channel connections (VCCs). A protection switchingstatus is received for each of the working and protection transmissionlinks. The virtual channel connections (VCCs) are selected from theworking and protection transmission links for processing by selectingthe virtual path connection (VPC) from one of the working and protectiontransmission links based on the protection switching status for at leastone of the working and protection transmission links.

More specifically, in accordance with a particular embodiment of thepresent invention, a virtual path group (VPG) is received on each of theworking and protection transmission links at the destination node. Thevirtual path group (VPG) includes the virtual path connection (VPC). Thevirtual path connection (VPC) is selected from the working andprotection transmission links by selecting the virtual path group (VPG)from one of the working and protection transmission links based on theprotection switching status for at least one of the working andprotection transmission links. In this embodiment, the virtual pathgroup (VPG) may be selected from the protection transmission link inresponse to receiving an alarm indication signal (AIS) for the workingtransmission link.

Technical advantages of the present invention include providing animproved protection architecture for virtual channel connections (VCCs)in a telecommunications network. In particular, virtual channelconnections (VCCs) are bundled together into a virtual path connection(VPC) that can be protection switched as a unit in response to atransmission line failure. Accordingly, only a single construct needs tobe protection switch and pathway selection is simplified at the terminusof the virtual channel connections (VCCs). In addition, configurationand management at intermediate nodes is simplified because many virtualchannel connections (VCCs) are tunneled into a single construct and theintermediate nodes see only the construct.

Other technical advantages of the present invention will be readilyapparent to one skilled in the art from the following figures,description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, wherein like referencenumerals represent like parts, in which:

FIG. 1 is a block diagram illustrating a telecommunications system inaccordance with one embodiment of the present invention;

FIG. 2 is a block diagram illustrating an add/drop multiplexer elementfor the telecommunications system of FIG. 1 in accordance with oneembodiment of the present invention;

FIG. 3 is a flow diagram illustrating a method for transmitting virtualchannel connections (VCCs) onto working and protecting transmissionlinks in accordance with one embodiment of the present invention; and

FIG. 4 is a flow diagram illustrating a method for protection switchingof virtual channel connections (VCCs) in accordance with one embodimentof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a telecommunications system 10 in accordance with oneembodiment of the present invention. In this embodiment, thetelecommunications system 10 comprises a public portion 12 and a privateportion 14 that each transmit voice, data, other suitable types ofinformation, and/or a combination of different types of information. Thepublic portion 12 includes a public network 20 such as the Internet. Theprivate portion 14 includes remote private networks 22 and 24. Theprivate networks 22 and 24 are each an Intranet or other suitablenetwork such as a private local area network (LAN) or a private widearea network (WAN). The telecommunications system 10 may be entirelyimplemented in either the public network 20 or in one of the privatenetworks 22 or 24, or may be otherwise suitably distributed betweendisparate networks.

Referring to FIG. 1, the telecommunications system 10 includes aplurality of nodes 26 interconnected by transmission lines 28. The nodes26 each comprise a network element (NE) capable of communicating trafficin the telecommunications system 10. The network element (NE) may be aswitch, router, add/drop multiplexer or other suitable device capable ofdirecting traffic in the telecommunications system 10.

The transmission lines 28 provide a physical interface between the nodes26. Each physical interface is defined by the bandwidth of theconnecting transmission line 28 which may be a DS-3 line, an OC-3 line,an OC-12 line, or any other suitable bandwidth. The transmission lines28 each comprise optical fiber, cable, twisted wire, or other suitablewireline or wireless link capable of transporting traffic between twonodes 26.

For the embodiment of FIG. 1, the telecommunications system 10 includesa source node 30 at a boundary of the private network 22, intermediatenodes 32 within the public network 20, and a destination node 34 at aboundary of the private network 24. The nodes 30, 32, and 34 are eachasynchronous transport mode (ATM) elements or multi-protocol elementshaving functionality for processing ATM traffic in which information isorganized into small, fixed length cells. The ATM cells are routed bythe nodes 30, 32, and 34, using a switching label included in the cell.The switching label has two sections that define a virtual path (VP) anda virtual channel (VC) in the telecommunications system 10 through whichthe cell is routed. Use of virtual paths (VPs) and virtual channels(VCs) allows physical bandwidth of the transmission lines 28 to besubdivided into virtual channel connections (VCCs) 36, virtual pathconnections (VPCs) 38, virtual path groups (VPGs) 40, and the like, andseparately commercialized.

The source and destination nodes 30 and 34 each include ATM switchfabric 42 that receives ATM traffic, performs address translation forswitching labels in the traffic, and transmits the traffic in accordancewith the translated switching labels. For the embodiment of FIG. 1, theATM switch fabric 42 at the source node 30 receives virtual channelconnection (VCC) traffic 36 destined for the destination node 34,translates the address labels in the virtual channel connections (VCCs)to designate a virtual path connection (VPC) 38 extending across aprotection domain defined between the source and destination nodes 30and 34 for the domain, and bridges the virtual path connection (VPC) 38onto a working transmission link 44 and a protection transmission link46 extending across the protection domain. The ATM switch fabric 42 mayalso include the virtual path connection (VPC) 38 by itself or withother traffic in a virtual path group (VPG) 40 defined across theprotection domain.

At the destination node 34, a virtual path (VP) selector 48 receives thevirtual path connection (VPC) 38 from the working and protectiontransmission links 44 and 46, selects the virtual channel connections(VCCs) 36 by selecting the virtual path connection (VPC) 38 from one ofthe links 44 or 46 based on a protection switching status for the links44 and/or 46. For the embodiment in which the virtual path connection(VPC) 38 is transmitted within the virtual path group (VPG) 40, thevirtual path (VP) selector 48 selects the virtual path connection (VPC)38 by selecting the virtual path group (VPG) 40. The ATM switch fabric42 at the destination node 34 separates the virtual channel connections(VCCs) received in the virtual path connection (VPC) 42 forindividualized routing to destination cards and links.

The protection switching status for the working and protectiontransmission links 44 and 46 are provided by an automatic protectionswitching (APS) virtual path connection (VPC) 45 for each of the workingand protection transmission links 44 and 46. The working and protectiontransmission links 44 and 46 may each include only the virtual pathconnection (VPC) 38, the virtual path connection (VPC) 38 along with itsassociated automatic protection switching (APS) virtual path connection(VPC) 45 or additional bandwidth. Each automatic protection switching(APS) virtual path connection (VPC) 45 may be bundled with thecorresponding virtual path connection (VPC) 38 in the virtual path group(VPG) 40 for transmission on the corresponding working and protectiontransmission link 44 or 46. As used herein, the term each means everyone of at least a subset of the identified items. It will be understoodthat the protection switching status may be otherwise suitably providedto the destination node 34.

In the destination node 34, the virtual path (VP) selector 48 by defaultselects the virtual path connection (VPC) 38 received from the workingtransmission link 44 unless an alarm indication signal (AIS) is receivedon the automatic protection switching (APS) virtual path connection(VPC) 45 for the working transmission link 44. The alarm indicationsignal (AIS) may be any suitable type of signal or indication that thecorresponding transmission link 44 or 46 has failed, is experiencingproblems, may be shut down, has become unreliable, and the like. Inresponse to the alarm indication signal (AIS), the virtual path (VP)selector 48 selects the virtual path connection (VPC) 38 received fromthe protection transmission link 46 and thereby selects all of theincluded virtual channel connections (VCC) 36 without individualizedprocessing. In the embodiment in which the virtual path connection (VPC)38 is transmitted within the virtual path group (VPG) 40, the virtualpath (VP) selector 48 responds to the alarm indication signal (AIS)selects the virtual path group (VPG) 40 and thereby selects all includedvirtual path connections (VPCs) 38 and virtual channel connections(VCCs). Accordingly, protection switching is performed for virtualchannel connections (VCCs) 36 at the virtual path connection (VPC) 38 orvirtual path group (VPG) 40 level. This eliminates the need toindividually protection switch virtual channel connections (VCCs) 36 andreduces resources that need be allocated to protection switching. Inaddition, the virtual channel connections (VCCs) 36 within the virtualpath connection (VPC) 38 tunnel are transparent to the intermediatenodes. This greatly simplifies the provisioning and administration ofthe intermediate nodes 32.

FIG. 2 illustrates details of the source and destination nodes 30 and 34in accordance with one embodiment of the present invention. In thisembodiment, the nodes 30 and 34 are each a multi-protocol add/dropmultiplexer 50. The add/drop multiplexer 50 includes a service complex52, a transport complex 54, switch complex 56, a management complex 58,and a synchronization complex 60. The disparate complexes 52, 54, 56,58, and 60 are interconnected by one or more networks or backplaneswithin the add/drop multiplexer 50.

The service complex 52 includes a plurality of tributary cards 62. Thetributary cards 62 each receive customer input/output (I/O) and performconversions necessary for processing by the switch complex 56.

The transport complex 54 includes a plurality of line cards 64 fortransmitting data on the transmission lines 66. In a particularembodiment, the line cards 64 are OC-3 or OC-12 line cards that arebi-directional and can handle optical to electrical (O/E) and electricalto optical (E/O) conversions. In this embodiment, the line cards 64 alsohandle the line and selection overhead extraction and insertion.

The switch complex 56 includes a plurality of switch fabrics includingan ATM switch fabric 68. The ATM switch fabric 68 may includefunctionality outside the switch complex 56 and is implemented in partby software stored in a computer-readable medium for execution by aprocessor of the add/drop multiplexer 50. The computer-readable mediumis a random access memory (RAM), a read only memory (ROM), or othersuitable medium capable of storing programming instructions forexecution by the processor.

The ATM switch fabric 68 includes a virtual path (VP) selector 70, ATMcross-connect 72, and bridging function 74. As previously described, thevirtual path (VP) selector 70 selects virtual channel connections (VCCs)36 for processing by the ATM switch fabric 68 by selecting a virtualpath connection (VPC) 38 and/or a virtual path group (VPG) 40 includingthe virtual channel connections (VCCS) 36.

The ATM switch fabric 68 receives ATM cells on an input port andswitches them to an output port using an ATM cross-connect 72. Inswitching the ATM cells, the ATM switch fabric 68 first translatesnecessary virtual path (VP) and virtual channel (VC) addresses in theswitching label of the ATM cells. The bridging function 74 transmits thevirtual channel connections (VCCs) 36, virtual path connection (VPC) 38,and/or virtual path group (VPG) 40 onto both the working and protectiontransmission links 44 and 46. In one embodiment, the bridging function74 is implemented by a 1:2 multicast within the ATM cross-connect 72. Inthis embodiment, each virtual path connection (VPC) tunnel is treated asa logical subport and handled by a scheduler on the ATM switch fabric68.

The management complex 58 monitors and controls the status of theservice, transport, switch, and synchronization complexes 52, 54, 56,and 60. The management complex 58 also maintains alarm, protectionswitching, and provisioning databases for the add/drop multiplexer 50.The synchronization complex 60 synchronizes the service, transport, andswitch complexes 52, 54, and 56 by providing a stable traceablereference clock.

FIG. 3 is a flow diagram illustrating a method for transmitting virtualchannel connections (VCCs) 36 onto working and protection transmissionlinks 44 and 46 in accordance with one embodiment of the presentinvention. In this embodiment, the virtual channel connections (VCCs) 36are combined into a virtual path connection (VPC) 38 which is thenincluded in a virtual path group (VPG) 40 for transmission over aprotected domain to a destination node 34. It will be understood thatthe virtual path connection (VPC) 38 containing the virtual channelconnections (VCCs) 36 may be otherwise suitably transmitted withoutinclusion in the virtual path group (VPG) 40.

Referring to FIG. 3, the method begins at step 80 in which virtualchannel connections (VCCs) 36 are received at the source node 30. Next,at step 82, virtual channel connections (VCCs) 36 of a specified typeare each provided with a common virtual path identifier (VPI) for adesignated virtual path connection (VPC) 38. The specified type may bethose of a particular user or group of users, service category or othersuitable characteristic that are together traversing the protectiondomain defined between the source and destination nodes 30 and 34.Provision of the common virtual path identifier (VPI) is provided by theATM switch fabric 68 in accordance with programmed switchinginstructions.

Proceeding to step 84, the virtual channel connections (VCCs) 36including the common virtual path identifier (VPI) are combined into thedesignated virtual path connection (VPC) 38. The virtual channelconnections (VCCs) 36 may be combined into the designated virtual pathconnection (VPC) 38 by bundling, tunneling, multiplexing, or any othersuitable process. At step 86, the virtual path connection (VPC) 38 isincluded by itself or with other traffic in a virtual path group (VPG)40 for transmission over the protected domain.

Proceeding to step 88, the virtual path group (VPG) 40 including thevirtual path connection (VPC) 38 and the included virtual channelconnections (VCCs) 36 are bridged onto the working and protectiontransmission links 44 and 46 to allow protection switching at thedestination node 34. Step 88 leads to the end of the process by whichvirtual channel connections (VCCs) 36 are packaged in a virtual pathconnection (VPC) 38 for transmission on working and protection links 44and 46 and switching between the links. Packaging of the virtual pathconnection (VPC) 38 into the virtual path group (VPG) 40 may be omitted.

FIG. 4 is a flow diagram illustrating a method for protection switchingof virtual channel connections (VCCs) 36 in accordance with oneembodiment of the present invention. In this embodiment, the virtualpath connections (VPCs) 38 containing the virtual channel connections(VCCs) 36 are transmitted within the virtual path group (VPG) 40. Itwill be understood that the virtual path connection (VPC) 38 may beindependently transmitted by the source node 30 and processed by thedestination node 34.

Referring to FIG. 4, the method begins at step 100 in which the virtualpath group (VPG) 40 is received at the destination node 34 on both theworking and protection transmission paths 44 and 46. As previouslydescribed, the virtual path group (VPG) 40 includes the virtual pathconnection (VPC) 38 and its included virtual channel connections (VCCs)36.

Proceeding to step 102, the destination node 34 monitors the automaticprotection switching (APS) virtual path connections (VPC) 45 for theworking and protection transmission links 44 and 46. At decisional step104, the destination node determines whether an alarm indication signal(AIS) has been received for the working transmission link. As previouslydiscussed, an alarm indication signal (AIS) indicates failure or othertype of problem on the working link 44. Accordingly, if an alarmindication signal (AIS) has been received for the working transmissionlink 44, the Yes branch of decisional step 104 leads to step 106 inwhich the virtual path (VP) selector 48 selects the virtual path group(VPG) 40 from the protection transmission link 46. If an alarmindication signal (AIS) has not been received for the workingtransmission link 44, the No branch of decisional step 104 leads to step108. At step 108, the virtual path (VP) selector 48 selects the virtualpath group (VPG) 40 of the working transmission link by default.Selection of the virtual path group (VPG) 40 on either the working orprotection transmission link 44 or 46 automatically selects the includedvirtual path connections (VPC) 38 and virtual channel connections (VCCs)36. Accordingly, protection switching for virtual channel connections(VCCs) 36 is conducted at the virtual path connection (VPC) 38 or higherlevel.

Proceeding to step 110, the destination node 34 processes the virtualpath connections (VPCs) 38 in the selected virtual path group (VPG) 40.In processing the virtual path connections (VPCs) 38, the destinationnode 34 processes the included virtual channel connections (VCCs) 36.Step 110 leads to the end of the process by which virtual channelconnections (VCCs) 36 are bundled together into a virtual pathconnection (VPC) 38 that is protection switched as a unit in response totransmission line failure. It will be understood that the method andsystem of the present invention may be used to provide a protectionarchitecture for other suitable types of virtual constructs in atelecommunications or other suitable system.

Although the present invention has been described with severalembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present invention encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method for protecting virtual channelconnection (VCC) traffic in a telecommunications system, comprising:receiving at a destination node a virtual path connection (VPC) on eachof a working transmission link and a protection transmission link, thevirtual path connection (VPC) including a plurality of virtual channelconnections (VCCs); receiving a protection switching status for each ofthe working and protection transmission links; and selecting the virtualchannel connections (VCCs) from the working and protection transmissionlinks for processing by selecting the virtual path connection (VPC) fromone of the working and protection transmission links based on theprotection switching status for at least one of the working andprotection transmission links.
 2. The method of claim 1, furthercomprising selecting the virtual path connection (VPC) from theprotection transmission link in response to receiving an alarmindication signal (AIS) for the working transmission link.
 3. The methodof claim 1, further comprising: receiving at the destination node avirtual path group (VPG) on each of the working and protectiontransmission links, the virtual path group (VPG) including the virtualpath connection (VPC); and selecting the virtual path connection (VPC)from the working and protection transmission links by selecting thevirtual path group (VPG) from one of the working and protectiontransmission links based on the protection switching status for at leastone of the working and protection transmission links.
 4. The method ofclaim 3, further comprising selecting the virtual path group (VPG) fromthe protection transmission link in response to receiving an alarmindication signal (AIS) for the working transmission link.
 5. The methodof claim 1, further comprising: receiving a working automatic protectionswitching (APS) virtual path connection (VPC) providing the protectionswitching status for the working transmission link; and receiving aprotection automatic protection switching (APS) virtual path connection(VPC) providing the protection switching status for the protectiontransmission link.
 6. The method of claim 5, further comprisingselecting the virtual path connection (VPC) from the protectiontransmission link in response to receiving an alarm indication signal(AIS) on the working automatic protection switching (APS) virtual pathconnection (VPC).
 7. The method of claim 1, further comprising: at asource node, receiving the plurality of virtual channel connections(VCCs); providing each of the virtual channel connections (VCCs) with acommon virtual path interface (VPI) designation the virtual pathconnection (VPC); combining the virtual channel connections (VCCs) intothe virtual path connection (VPC); and bridging the virtual pathconnection (VPC) onto the working and protection transmission links fortransmission to the destination node.
 8. The method of claim 7, furthercomprising: at the source node, including the virtual path connection(VPC) in a virtual path group (VPG); bridging the virtual path group(VPG) onto the working and protection transmission links fortransmission to the destination node; at the destination node, receivingthe virtual path group (VPG) on each of the working and protectiontransmission links; and selecting the virtual path connection (VPC) fromthe working and protection transmission links by selecting the virtualpath group (VPG) from one of the working and protection transmissionlinks based on the protection switching status for at least one of theworking and protection transmission links.
 9. The method of claim 7,combining the virtual channel connections (VCCs) into the virtual pathconnection (VPC) comprising multiplexing the virtual channel connections(VCCs) into the virtual path connection (VPC).
 10. A telecommunicationsnode, comprising: a virtual path (VP) selector comprising softwarestored on a computer-readable medium, the virtual path selector operableto receive on each of a working transmission link and a protectiontransmission link a virtual path connection (VPC) including a pluralityof virtual channel connections (VCCs), to receive a protection switchingstatus for each of the working and protection transmission links, and toselect the virtual channel connections (VCCs) from the working andprotection transmission links for processing by selecting the virtualpath connection (VPC) from one of the working and protectiontransmission links based on the protection switching status for at leastone of the working and protection transmission links; and anasynchronous transfer mode (ATM) cross-connect operable to receive andprocess the virtual channel connections (VCCs) selected by the virtualpath (VP) selector.
 11. The telecommunications node of claim 10, thevirtual path (VP) selector further operable to select the virtual pathconnection (VPC) from the protection transmission link in response toreceiving an alarm indication signal (AIS) for the working transmissionlink.
 12. The telecommunications node of claim 10, the virtual path (VP)selector further operable to receive on each of the working andprotection transmission links a virtual path group (VPG) including thevirtual path connection (VPC) and to select the virtual path connection(VPC) from the working and protection transmission links by selectingthe virtual path group (VPG) from one of the working and protectiontransmission links based on the protection switching status for at leastone of the working and protection transmission links.
 13. Thetelecommunications node of claim 12, the virtual path (VP) selectorfurther operable to select the virtual path group (VPG) from theprotection transmission link in response to receiving an alarmindication signal (AIS) for the working transmission link.
 14. Thetelecommunications node of claim 10, the virtual path (VP) selectorfurther operable to receive a working automatic protection switching(APS) virtual path connection (VPC) providing the protection switchingstatus for the working transmission link and a protection automaticprotection switching (APS) virtual path connection (VPC) providing theprotection switching status for the protection transmission link. 15.The telecommunications node of claim 14, the virtual path (VP) selectorfurther operable to select the virtual path connection (VPC) from theprotection transmission link in response to receiving an alarmindication signal (AIS) on the working automatic protection switching(APS) virtual path connection (VPC).
 16. A telecommunications system,comprising: a working transmission link and a protection transmissionlink each connecting a source node and a destination node; the sourcenode including an asynchronous transfer mode (ATM) switch fabriccomprising software stored on a computer-readable medium, theasynchronous transfer mode (ATM) switch fabric operable to receive aplurality of virtual channel connections (VCCs), provide each of thevirtual channel connections (VCCs) with a virtual path identifier (VPI)for a virtual path connection (VPC), combine the virtual channelconnections (VCCs) into the virtual path connection (VPC), and bridgethe virtual path connection (VPC) onto the working and protectiontransmission links for transmission to the destination node; and thedestination node including a virtual path (VP) selector comprisingsoftware stored on a computer-readable medium, the virtual path selectoroperable to receive the virtual path connection (VPC) on each of theworking and protection transmission links, to receive a protectionswitching status for each of the working and protection transmissionlinks, and to select the virtual channel connections (VCCs) from theworking and protection transmission links for processing by selectingthe virtual path connection (VPC) from one of the working and protectiontransmission links based on the protection switching status for at leastone of the working and protection transmission links.
 17. Thetelecommunications system of claim 16, further comprising: theasynchronous transfer mode (ATM) switch fabric further operable toinclude the virtual path connection (VPC) in a virtual path group (VPG)and bridge the virtual path group (VPG) onto the working and protectiontransmission links for transmission to the destination node; and thevirtual path (VP) selector further operable to receive the virtual pathgroup (VPG) on each of the working and protection transmission links andto select the virtual path connection (VPC) from the working andprotection transmission links by selecting the virtual path group (VPG)from one of the working and protection transmission links based on theprotection switching status for at least one of the working andprotection transmission links.
 18. The telecommunications system ofclaim 17, the virtual path (VP) selector further operable to select thevirtual path group (VPG) from the protection transmission link inresponse to receiving an alarm indication signal (AIS) for the workingtransmission link.
 19. The telecommunications system of claim 16,further comprising: a working automatic protection switching (APS)virtual path connection (VPC) providing the protection switching statusfor the working transmission link to the destination node; a protectionautomatic protection switching (APS) virtual path connection (VPC)providing the protection switching status for the protectiontransmission link to the destination node; and the virtual path (VP)selector further operable to select the virtual path connection (VPC)from the protection transmission link in response to receiving an alarmindication signal (AIS) on the working automatic protection switching(APS) virtual path connection (VPC).
 20. The telecommunications systemof claim 16, the asynchronous transfer mode (ATM) switch fabric furthercomprising a multiplexer operable to multiplex the virtual channelconnections (VCCs) into the virtual path connection (VPC).